As a follow-on to he previous answer, the Guest OS does have a virtual Network Interface Card (NIC). This "guest NIC" has a MAC address which differs from that of the host OS.

An alternative would, if you have access to the router settings, to let the router allocate the the same IP address to that MAC address every time it requests one via DHCP. NB I haven't tried this myself but it should work.

It comes down to where you prefer to do the configuration, in the router or in the guest OS.